fix(chat): use ~/.codex/skills/ for Codex expert symlinks and keep expert button always enabled

Change Codex skill storage to use only ~/.codex/skills/ instead of
~/.agents/skills/, and never disable the expert skills button so users
can always access the empty-state hint. Also fix stale expert list in
conversation window after linking in the separate settings window by
re-fetching on window focus.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/chat/message-input.tsx

@@ -1757,7 +1757,7 @@ export function MessageInput({
             <DropdownMenu>
               <DropdownMenuTrigger asChild>
                 <Button
-                  disabled={disabled || availableExperts.length === 0}
+                  disabled={disabled}
                   variant="outline"
                   size="icon"
                   className="h-6 w-6 shrink-0 bg-transparent"

src/hooks/use-agent-experts.ts

@@ -1,6 +1,6 @@
 "use client"
 
-import { useEffect, useMemo, useState } from "react"
+import { useCallback, useEffect, useMemo, useState } from "react"
 
 import { expertsListForAgent } from "@/lib/api"
 import type { AgentType, ExpertListItem } from "@/lib/types"
@@ -10,6 +10,25 @@ const inflightMap = new Map<AgentType, Promise<ExpertListItem[]>>()
 
 const EMPTY: ExpertListItem[] = []
 
+function fetchForAgent(agentType: AgentType): Promise<ExpertListItem[]> {
+  let promise = inflightMap.get(agentType)
+  if (!promise) {
+    promise = expertsListForAgent(agentType)
+      .then((list) => {
+        agentCache.set(agentType, list)
+        inflightMap.delete(agentType)
+        return list
+      })
+      .catch((err) => {
+        inflightMap.delete(agentType)
+        console.warn("[useAgentExperts] failed:", err)
+        return EMPTY
+      })
+    inflightMap.set(agentType, promise)
+  }
+  return promise
+}
+
 export function useAgentExperts(agentType: AgentType | null): ExpertListItem[] {
   const cached = useMemo(
     () => (agentType ? (agentCache.get(agentType) ?? null) : null),
@@ -22,35 +41,34 @@ export function useAgentExperts(agentType: AgentType | null): ExpertListItem[] {
     experts: ExpertListItem[]
   } | null>(null)
 
-  useEffect(() => {
+  const doFetch = useCallback(() => {
     if (!agentType || agentCache.has(agentType)) return
-
     let cancelled = false
-    let promise = inflightMap.get(agentType)
-    if (!promise) {
-      promise = expertsListForAgent(agentType)
-        .then((list) => {
-          agentCache.set(agentType, list)
-          inflightMap.delete(agentType)
-          return list
-        })
-        .catch((err) => {
-          inflightMap.delete(agentType)
-          console.warn("[useAgentExperts] failed:", err)
-          return EMPTY
-        })
-      inflightMap.set(agentType, promise)
-    }
-
-    promise.then((list) => {
+    fetchForAgent(agentType).then((list) => {
       if (!cancelled) setFetched({ agentType, experts: list })
     })
-
     return () => {
       cancelled = true
     }
   }, [agentType])
 
+  // Initial fetch
+  useEffect(() => doFetch(), [doFetch])
+
+  // Re-fetch when window regains focus (covers cross-window cache
+  // invalidation — e.g. settings window links/unlinks experts while the
+  // conversation window stays mounted).
+  useEffect(() => {
+    const onFocus = () => {
+      if (!agentType) return
+      agentCache.delete(agentType)
+      inflightMap.delete(agentType)
+      doFetch()
+    }
+    window.addEventListener("focus", onFocus)
+    return () => window.removeEventListener("focus", onFocus)
+  }, [agentType, doFetch])
+
   if (!agentType) return EMPTY
   if (cached) return cached
   if (fetched && fetched.agentType === agentType) return fetched.experts